40.5. VAX Branch Improvement

Certain pseudo opcodes are permitted. They are for branch
instructions. They expand to the shortest branch instruction that
reaches the target. Generally these mnemonics are made by
substituting j for b at the start of a DEC mnemonic.
This feature is included both for compatibility and to help
compilers. If you do not need this feature, avoid these
opcodes. Here are the mnemonics, and the code they can expand into.

jbsb

Jsb is already an instruction mnemonic, so we chose jbsb.

(byte displacement)

bsbb …

(word displacement)

bsbw …

(long displacement)

jsb …

jbr, jr

Unconditional branch.

(byte displacement)

brb …

(word displacement)

brw …

(long displacement)

jmp …

jCOND

COND may be any one of the conditional branches
neq, nequ, eql, eqlu, gtr,
geq, lss, gtru, lequ, vc, vs,
gequ, cc, lssu, cs.
COND may also be one of the bit tests
bs, bc, bss, bcs, bsc, bcc,
bssi, bcci, lbs, lbc.
NOTCOND is the opposite condition to COND.